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	<div id="winchm_template_button"><A href="getshortfield.htm" title="Previous topic"><img id="winchm_template_prev" alt="Previous topic" src="../template2/btn_prev_n.gif" border="0"></a><A href="readlistentry.htm" title="Next topic"><img id="winchm_template_next" alt="Next topic" src="../template2/btn_next_n.gif" border="0"></a></div>
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<A href="introduction6.htm">Debugging Tools for Windows (WinDbg, KD, CDB, NTSD)</A> &gt; <A href="debugging_resources.htm">Debugging Resources</A> &gt; <A href="debugger_engine_and_extension_apis.htm">Debugger Engine and Extension APIs</A> &gt; <A href="writing_wdbgexts_extensions.htm">Writing WdbgExts Extensions</A> &gt; <A href="wdbgexts_extension_reference.htm">WdbgExts Extension Reference</A> &gt; <A href="wdbgexts_functions.htm">WdbgExts Functions</A> &gt; </div>
	<div id="winchm_template_title">ReadField</div>
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	<div id="winchm_template_content"><div id="mainSection"><p>The <b>ReadField</b> and <b>ReadFieldStr</b> macros read a field whose size is less than 8 bytes from a structure initialized with <a href="#Bookmark1130"><b>InitTypeRead</b></a> or <a href="#Bookmark1132"><b>InitTypeReadPhysical</b></a>. </p>
<pre class="syntax" xml:space="preserve"><code>#define ReadField(Field) \
    GetShortField(0, #Field, 0)

#define ReadFieldStr(FieldStr) \
    GetShortField(0, FieldStr, 0)</code></pre>
<h2><a id="Parameters"></a><a id="parameters"></a><a id="PARAMETERS"></a>Parameters</h2>
<dl>
<dd>Field<dl>
<dd>Specifies the name of the field.  The C-preprocessor will turn <i>Field</i> into a string.</dd>
</dl>
</dd>
<dd>FieldStr<dl>
<dd>Specifies the name of the field.  <i>FieldStr</i> is expected to be an ASCII string. </dd>
</dl>
</dd>
</dl>
<h2><a id="ddk_getdebuggerdata_dbwx"></a><a id="DDK_GETDEBUGGERDATA_DBWX"></a></h2>
<h3><a id="Return_Value"></a><a id="return_value"></a><a id="RETURN_VALUE"></a>Return Value</h3>
<p>If this macro succeeds, it returns the value of the specified field in the previously initialized structure. The structure is the one initialized in a previous call to <a href="#Bookmark1130"><b>InitTypeRead</b></a>, <b>InitTypeStrRead</b>, <a href="#Bookmark1132"><b>InitTypeReadPhysical</b></a>, <b>InitTypeStrReadPhysical</b>, or <a href="#Bookmark1122"><b>GetShortField</b></a>.  The field is the one specified by the <i>Field</i> or <i>FieldStr</i> parameter of <b>ReadField</b>.  The return value is cast to ULONG64.  If the function fails, it returns the value zero. </p>
<h2>Remarks</h2>
<p>The parameter <i>Field</i> is the name of the member.  For <b>ReadField</b>, the C pre-processor will turn the parameter into a string.  For <b>ReadFieldStr</b>, <i>Field</i> is expected to already be an ASCII string.  For example, the following two commands are identical and read the same member from a previously initialized structure:</p>
<p>
<ul>
<li>ReadField( myField );</li>
<li>ReadFieldStr( "myField" );</li>
</ul>
</p>
<p>Submembers can be read by using a period-separated path, for example, "myField.mySubfield".</p>
<div class="alert"><b>Note</b>    Because these macros use the <a href="#Bookmark1122"><b>GetShortField</b></a> function, they must be called from the same source code file as the macros that initialize the structure for reading.  For more details, see <b>GetShortField</b>.</div>
<div> </div>
<p>If you are writing a WdbgExts extension, include <b>wdbgexts.h</b>. If you are writing a DbgEng extension that calls this function, include <b>wdbgexts.h</b> before <b>dbgeng.h</b> (see <a href="#Bookmark916">Writing DbgEng Extension Code</a> for details).
</p>
<h2>Requirements</h2>
<table>
<tr>
<th width="30%">
<p>Header</p>
</th>
<td width="70%">
<dl>
<dt>Wdbgexts.h (include Wdbgexts.h, Wdbgexts.h, or Dbgeng.h)</dt>
</dl>
</td>
</tr>
</table>
<h2><a id="see_also"></a>See also</h2>
<dl>
<dt><a href="#Bookmark1130"><b>InitTypeRead</b></a></dt>
<dt><a href="#Bookmark1132"><b>InitTypeReadPhysical</b></a></dt>
<dt><a href="#Bookmark1122"><b>GetShortField</b></a></dt></dl></div></div>	
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